How much is too much, milling heads?

Fett

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Nov 2, 2004

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Apr 26, 2005

#1

• Apr 26, 2005

• #1

If you have stock heads, how far is too far before you start having issues with clearance and mounting intake?

In other words, if you took stock heads and had them milled 30-thousands, used stock pushrods and lifters, and bolt-down 1.7 rockers....would you have any issues mounting the intake or any problems with the rockers hitting stock covers?

I am trying to solve a problem I ran into because one of the heads I used was milled down WAY too much. I am deciding between a few choices in replacement heads, and wonder about milling. Everything I read says that 30 thousands down is good for compression, but I don't want to run into any issues mounting the intake or having to shim the bolt-down rockers.

 

Zero_chance

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May 29, 2001

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Apr 27, 2005

#2

• Apr 27, 2005

• #2

Im pretty sure you have to take some material off the intake to match what was taken off the heads.

 

T

TbonesBlack92GT

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Apr 19, 2005

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Apr 27, 2005

#3

• Apr 27, 2005

• #3

I have read that over .020 and you should mill the intake too. I had .020 milled off of my Winsdsor Jrs. (now 53 cc) and did nothing to the intake with no problems. I am running Stage 1 cam (.499/.512 lift) with plenty of clearance.
Anything over .020 should be checked (actually, you should check it anyway).

 

jaymac

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Feb 18, 2004

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Apr 27, 2005

#4

• Apr 27, 2005

• #4

subscribed.
My stuff is at the shop right now awaiting instructions....

 

Fett

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Apr 29, 2005

#5

• Apr 29, 2005

• #5

TbonesBlack92GT said:

I have read that over .020 and you should mill the intake too. I had .020 milled off of my Winsdsor Jrs. (now 53 cc) and did nothing to the intake with no problems. I am running Stage 1 cam (.499/.512 lift) with plenty of clearance.
Anything over .020 should be checked (actually, you should check it anyway).

Click to expand...

That is pretty much what I want to do. I want to take advantage of higher compression, but I don't want to get into any situations where I have clearance issues, or problems mounting the intake and causing leaks. So on one hand I just want the heads resurfaced, on the other I want to mill as much as I can without running into any problems.

 

jaymac

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Apr 30, 2005

#6

• Apr 30, 2005

• #6

so does anybody have any solid info on this?

 

jb89coupe

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Apr 30, 2005

#7

• Apr 30, 2005

• #7

My powerheads are milled .040". I used a gt40 intake, stock rods and rockers on them with no issues.

 

jaymac

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Apr 30, 2005

#8

• Apr 30, 2005

• #8

sweet!

 

jb89coupe

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Apr 30, 2005

#9

• Apr 30, 2005

• #9

The only thing to note is that the gaps at the end seals (where the lower meets the block) were pretty big. I sandwiched the cork gaskets that came with the intake set between two huge beads of rtv. I put the lower on and snugged all the bolts, let it sit overnight, and torqued it to spec the next day. So far no leaks. You also may need to shim your rockers, but no big deal!

 

jaymac

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#10

• Apr 30, 2005

• #10

did you shim your rockers?
How many/what size?
Thanks!

 

Blk91stang

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Apr 30, 2005

#11

• Apr 30, 2005

• #11

jb89coupe said:

The only thing to note is that the gaps at the end seals (where the lower meets the block) were pretty big. I sandwiched the cork gaskets that came with the intake set between two huge beads of rtv. I put the lower on and snugged all the bolts, let it sit overnight, and torqued it to spec the next day. So far no leaks. You also may need to shim your rockers, but no big deal!

Click to expand...

I also have powerheads shaved to 58cc with no sealing problems. Also the most preferred way of sealing the lower intake ends is without the cork and only a bead of rtv. Make sure when you lay down the lower intake gaskets to put rtv around the water ports on both sides of the gasket! You should be fine milling the head that much.

 

jaymac

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Apr 30, 2005

#12

• Apr 30, 2005

• #12

what if I went to 55 cc's?

 

jaymac

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May 24, 2005

#13

• May 24, 2005

• #13

jb89, any more details on shimming rockers before I jump in?

 

T

tjm73

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May 24, 2005

#14

• May 24, 2005

• #14

No one has mentioned it, but milling the head reduces the ammount of material between the firedeck and the water jackets. You don't want that to get too thin.

Anyone know how thick the heads are in the firedeck?

 

jaymac

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May 24, 2005

#15

• May 24, 2005

• #15

Something I didn't know... Anybody w/ a credible answer to that?

 

T

tjm73

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May 24, 2005

#16

• May 24, 2005

• #16

I know if it gets too thin it can contribute to head gasket sealing problems. Especially if 'the sauce' or boost is used.

 

jaymac

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May 24, 2005

#17

• May 24, 2005

• #17

#'s anyone?